带有副本集的PHP MongoClient“未找到候选服务器”

Question

规格：PHP 5.3.10、Ubuntu 12.04 64 位、Mongo 驱动程序 1.5.1、MongoDB 2.4.8

我们有一个带有两个辅助副本集的 Mongo 分片。我似乎无法让 PHP 驱动程序利用副本集进行高性能读/写。尝试使用下面提供的连接字符串进行连接时，我收到“未找到候选服务器”。

$connection = new MongoClient("mongodb://10.88.217.247:27017,10.88.217.247:27018",
                            array('username'=>"{$username}", 'password'=>"{$password}", 'replicaSet' => true));

这是 Mongo 日志发送的内容：

[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: start
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] send_packet: read from header: 36
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] send_packet: data_size: 259
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: can't find minWireVersion, defaulting to 0
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: can't find maxWireVersion, defaulting to 0
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: setting maxBsonObjectSize to 16777216
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: setting maxMessageSizeBytes to 48000000
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: can't find maxWriteBatchSize, defaulting to 1000
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: set name: rs-0, ismaster: 1, secondary: 0, is_arbiter: 0
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: the server name (mongo-0-0:27018) did not match with what we thought it'd be (10.88.218.248:27018).
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: the replicaset name is not set, so we're using rs-0.
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] found host: mongo-0-0:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] found host: mongo-0-2:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] found host: mongo-0-1:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] ismaster: last ran at 1398292169
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] discover_topology: ismaster worked, but we need to remove the seed host's connection
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] mongo_connection_destroy: Destroying connection object for 10.88.218.248:27018;-;admin/scal/a6612d715d1a4f9549232ec4d599bf55;12199
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] mongo_connection_destroy: Closing socket for 10.88.218.248:27018;-;admin/scal/a6612d715d1a4f9549232ec4d599bf55;12199.
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] discover_topology: ismaster worked
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] discover_topology: found new host: mongo-0-0:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.2.122] connection_create: creating new connection for mongo-0-0:27018

rs.status() JSON：

 {
"set" : "rs-0",
"date" : ISODate("2014-04-24T15:13:39.000Z"),
"myState" : 1,
"members" : [ 
    {
        "_id" : 0,
        "name" : "mongo-0-0:27018",
        "health" : 1,
        "state" : 1,
        "stateStr" : "PRIMARY",
        "uptime" : 68415,
        "optime" : Timestamp(1398285029, 1),
        "optimeDate" : ISODate("2014-04-23T20:30:29.000Z"),
        "self" : true
    }, 
    {
        "_id" : 1,
        "name" : "mongo-0-1:27018",
        "health" : 1,
        "state" : 2,
        "stateStr" : "SECONDARY",
        "uptime" : 67984,
        "optime" : Timestamp(1398285029, 1),
        "optimeDate" : ISODate("2014-04-23T20:30:29.000Z"),
        "lastHeartbeat" : ISODate("2014-04-24T15:13:38.000Z"),
        "lastHeartbeatRecv" : ISODate("2014-04-24T15:13:38.000Z"),
        "pingMs" : 0,
        "syncingTo" : "mongo-0-0:27018"
    }, 
    {
        "_id" : 3,
        "name" : "mongo-0-2:27018",
        "health" : 1,
        "state" : 2,
        "stateStr" : "SECONDARY",
        "uptime" : 63419,
        "optime" : Timestamp(1398285029, 1),
        "optimeDate" : ISODate("2014-04-23T20:30:29.000Z"),
        "lastHeartbeat" : ISODate("2014-04-24T15:13:38.000Z"),
        "lastHeartbeatRecv" : ISODate("2014-04-24T15:13:38.000Z"),
        "pingMs" : 0,
        "syncingTo" : "mongo-0-0:27018"
    }
],
"ok" : 1

}

Answer 1

设置副本集时可能需要注意的几件事：

• 在构建副本集时，第一个成员将使用服务器的主机名命名。所以当你访问服务器时，它会不访问连接字符串中的主机。相反，它从那里获取可用服务器列表，并尝试连接到该列表中的主机名。我解释了一些细节here。您也可以在mongodb c# driver tutorial 中找到信息：

要求每个 MongoDB 服务器都有一个可由客户端机器 DNS 解析的名称。每个 MongoDB 服务器通过 isMaster 命令报告其主机名，驱动程序使用此名称与服务器通信。当种子列表包含 IP 地址并且 MongoDB 服务器报告客户端计算机无法解析的主机名时，可能会出现此问题。

• 当您访问一个副本集时，您应该提供一个带有参数replicaSet=[set name] 的副本集名称，如下所示。

  mongodb://hostname1,hostname2/dbName?replicaSet=rs0
  

• 不要混淆来自不同副本集的服务器，因为：

如果您列出了多个服务器，其中一个是副本集的一部分而另一个不是，则连接模式是不确定的。确保您没有在连接字符串上混合服务器类型。

• 记下你的 mongo 服务器的绑定 ip。如果我没记错的话，在某些发行版中它默认监听 127.0.0.1:27017。因此，您将永远无法从访客机器上获得连接。尝试在 /etc/mongodb.conf 中设置以下行：

  bind_ip = 0.0.0.0

回到你的问题。来自日志：

[Wed Apr 23 22:29:29 2014] [error] [client 170.171.1.123] ismaster: the replicaset name is not set, so we're using rs-0.

它告诉您提供副本集名称。它假定它是 rs-0（名称正确吗？）

[Wed Apr 23 22:29:29 2014] [error] [client 170.171.1.123] found host: mongo-0-0:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.1.123] found host: mongo-0-2:27018
[Wed Apr 23 22:29:29 2014] [error] [client 170.171.1.123] found host: mongo-0-1:27018

说您的副本集中有 3 个成员。驱动程序将使用他们的名字连接到他们，这将是：

mongo-0-0:27018
mongo-0-1:27018
mongo-0-2:27018

如果您希望它们工作，请添加到您客户的 /etc/hosts

[ip of mongo] mongo-0-0:27018
[ip of mongo] mongo-0-0:27018
[ip of mongo] mongo-0-0:27018

或者，如果您想更改这些名称，请使用以下行：

var conf = rs.conf();
conf.members[0].host = "..." // your new name for member0
conf.member[1].host = "..."
conf.member[2].host = "..."
rs.reconfig(conf)